Sugarcane/soybean intercropping with reduced nitrogen addition is an important sustainable agricultural pattern that can alter soil ecological functions,thereby affecting straw decomposition in the soil.However,the me...Sugarcane/soybean intercropping with reduced nitrogen addition is an important sustainable agricultural pattern that can alter soil ecological functions,thereby affecting straw decomposition in the soil.However,the mechanisms underlying changes in soil organic carbon(SOC)composition and microbial communities during straw decomposition under long-term intercropping with reduced nitrogen addition remain unclear.In this study,we conducted an in-situ microplot incubation experiment with^(13)C-labeled soybean straw residue addition in a two-factor(cropping pattern:sugarcane monoculture(MS)and sugarcane/soybean intercropping(SB);nitrogen addition levels:reduced nitrogen addition(N1)and conventional nitrogen addition(N2))long-term experimental field plot.The results showed that the SBN1 treatment significantly increased the residual particulate organic carbon(POC)and residual microbial biomass carbon(MBC)contents during straw decomposition,and the straw carbon in soil was mainly conserved as POC.Straw addition changed the structure and reduced the diversity of the soil microbial community,but microbial diversity gradually recovered with decomposition time.During straw decomposition,the intercropping pattern significantly increased the relative abundances of Firmicutes and Ascomycota.In addition,straw addition reduced microbial network complexity in the sugarcane/soybean intercropping pattern but increased it in the sugarcane monoculture pattern.Nevertheless,microbial network complexity remained higher in the SBN1 treatment than in the MSN1 treatment.In general,the SBN1 treatment significantly increased the diversity of microbial communities and the relative abundance of microorganisms associated with organic matter decomposition,and the changes in microbial communities were mainly driven by the residual labile SOC fractions.These findings suggest that more straw carbon can be sequestered in the soil under sugarcane/soybean intercropping with reduced nitrogen addition to maintain microbial diversity and contribute to the development of sustainable agriculture.展开更多
The ATP-binding cassette(ABC)transporter is a gene superfamily in plants.ATP-binding cassette subfamily C(ABCC)protein is a multidrug resistance-associated(MRP)transporter.They play various roles in plant growth,devel...The ATP-binding cassette(ABC)transporter is a gene superfamily in plants.ATP-binding cassette subfamily C(ABCC)protein is a multidrug resistance-associated(MRP)transporter.They play various roles in plant growth,development,and secondary metabolite transport.However,there are few studies on ABCC transporters in tea plants.In this study,genome-wide association study(GWAS)analysis of epigallocatechin gallate(EGCG)content in 108 strains of Kingbird revealed that CsABCCs may be involved in EGCG transport.We identified 25 CsABCC genes at the genomic level of the tea plant,their phylogenetic tree,gene structure,targeted miRNA and other bioinformatics were analyzed.The expression patterns of CsABCCs in eight different tissues and abiotic stress indicate that they have potential roles in regulating the growth,development,and defense of tea plants.The correlation analysis revealed that the expression of the CsABCC11 gene was closely related to the EGCG content in tea buds of 108 strains of the Kingbird,and the subcellular localization experiments in tobacco showed that CsABCC11 protein was localized on the plasma membrane.The virus-induced gene silencing(VIGS)strategy in tea plants further verified that CsABCC11 was involved in EGCG accumulation.Our study laid a foundation for studying the biological function of CsABCC and provided a new candidate molecular marker gene for further EGCG-related variety breeding,which will be of great interest to breeders.展开更多
The study explored the influence of defatted flaxseed gum powder(DFGP) on the stability and quality of sesame paste by measuring and analyzing its composition, color, texture, particle size, centrifugal oil separation...The study explored the influence of defatted flaxseed gum powder(DFGP) on the stability and quality of sesame paste by measuring and analyzing its composition, color, texture, particle size, centrifugal oil separation rate,rheological properties, and microstructure. The results showed that the moisture and polysaccharide content of sesame paste was increased as the DFGP increased. Additionally, the hardness, gumminess, and chewiness of the sesame paste was improved, while the presence of particles with small particle size(1–100 μm) was decreased.The rate of oil precipitation was reduced by 28.99% when the amount of DFGP was 6%. The sesame paste samples exhibited pseudoplastic behavior, demonstrating shear thinning. As the shear rate increased, the apparent viscosity of sesame paste gradually decreased. Both the storage modulus(G’) and the loss modulus(G’’) increased as the shear frequency increased. The microstructure observation revealed that protein and oil were evenly distributed in the sesame paste system, and the addition of DFGP enhanced the bonding between oil and protein.This study can provide valuable references for high-quality sesame paste products in the food industry.展开更多
Caffeine is considered as one of the most important bioactive components in the popular plant beverages tea,cacao,and coffee,but as a wide-spread plant secondary metabolite its biosynthetic regulation at transcription...Caffeine is considered as one of the most important bioactive components in the popular plant beverages tea,cacao,and coffee,but as a wide-spread plant secondary metabolite its biosynthetic regulation at transcription level remains largely unclear.Here,we report a novel transcription factor Camellia sinensis Senescnece 40(CsS40)as a caffeine biosynthesis regulator,which was discovered during screening a yeast expression library constructed from tea leaf cDNAs for activation of tea caffeine synthase(TCS1)promoter.Besides multiple hits of the non-self-activation CsS40 clones that bound to and activated TCS1 promoter in yeast-one-hybrid assays,a split-luciferase complementation assay demonstrated that CsS40 acts as a transcription factor to activate the CsTCS1 gene and EMSA assay also demonstrated that CsS40 bound to the TCS1 gene promoter.Consistently,immunofluorescence data indicated that CsS40-GFP fusion was localized in the nuclei of tobacco epidermal cells.The expression pattern of CsS40 in‘Fuding Dabai’developing leaves was opposite to that of TCS1;and knockdown and overexpression of CsS40 in tea leaf calli significantly increased and decreased TCS1 expression levels,respectively.The expression levels of CsS40 were also negatively correlated to caffeine accumulation in developing leaves and transgenic calli of‘Fuding Dabai’.Furthermore,overexpression of CsS40 reduced the accumulation of xanthine and hypoxanthine in tobacco plants,meanwhile,increased their susceptibility to aging.CsS40 expression in tea leaves was also induced by senescence-promoting hormones and environmental factors.Taken together,we showed that a novel senescence-related factor CsS40 negatively regulates TCS1 and represses caffeine accumulation in tea cultivar‘Fuding Dabai’.The study provides new insights into caffeine biosynthesis regulation by a plant-specific senescence regulator in tea plants in connection to leaf senescence and hormone signaling.展开更多
δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to und...δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle.δ-(Al_(0.956)Fe_(0.044))OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells.The incorporation of 5 mol%FeOOH increases the unit-cell volume ofδ-AlOOH by~1%and decreases the shear-wave velocity(VS)by~5%at 20–135 GPa.In particular,the compressional(V_(P))and shear(VS)wave velocities ofδ-(Al_(0.956)Fe_(0.044))OOH are 7%–16%and 10%–24%greater than all the major minerals in the mantle transition zone including wadsleyite,ringwoodite,and majorite.The distinctly high sound velocities ofδ-(Al_(0.956)Fe_(0.044))OOH at 20–25 GPa may contribute to the seismic anomalies observed at~560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea.Furthermore,the VS ofδ-(Al_(0.956)Fe_(0.044))OOH is about 10%and 4%–12%lower than iron-bearing bridgmanite Mg_(0.96)Fe_(0.05)Si_(0.99O3)and ferropericlase(Mg_(0.92)Fe_(0.08))O,respectively,under the lowermost mantle conditions,which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.展开更多
Being an emerging body-shaping technology of fat cell disruption,high-intensity focused ultrasound has been investigated intensively in recent years for its favorable natures such as painlessness,safety and noninvasio...Being an emerging body-shaping technology of fat cell disruption,high-intensity focused ultrasound has been investigated intensively in recent years for its favorable natures such as painlessness,safety and noninvasion.One of the major problems for the technology,however,is the overheating of transducers.In this study,we modified the transducer design in order to solve the overheating problem.We simulated the performance of the modified design by finite element analysis and fabricated the newly designed transducer.By measuring the actual performance data,we proved that the new design can effectively reduce temperature rise while keeping the acoustic intensity field unaffected.展开更多
The collapse of granular material in fluids is a prevalent phenomenon in both natural and industrial processes,displaying a notable sensitivity to initial configuration of the system.This study is specifically oriente...The collapse of granular material in fluids is a prevalent phenomenon in both natural and industrial processes,displaying a notable sensitivity to initial configuration of the system.This study is specifically oriented towards falling process of collapsing material under various fluid conditions,employing the computational fluid dynamics-discrete element method(CFD-DEM)to primarily investigate the dynamics and scaling laws of deposit morphology of collapsed material.Through a comprehensive analysis of particle sedimentation in fluids,we introduce a refined inertial characteristic time for granular collapse within the inertial regime.Subsequently,we propose modifications to conventional fluid-particle density ratio and Reynolds number,aiming to enhance the accuracy of depicting collapse dynamics and identifying flow regimes across diverse column heights and fluid conditions.Finally,we construct a phase diagram of flow regimes using modified dimensionless numbers,emphasizing the role of column height in transition between viscous and inertial regimes.These parameters demonstrate enhanced relevance in governing the collapse of immersed granular columns,thereby contributing to a more nuanced understanding of fluid-particle interations in dense granular flows under different regimes.展开更多
Recently,high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness,fracture toughness,and conductivity.However,as a newly emerging class of...Recently,high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness,fracture toughness,and conductivity.However,as a newly emerging class of materials,the synthesis,performance and applications of high-entropy ceramics are subject to further development.Here,we reported a new non-stoichiometric TiC0.4/WC/0.5Mo2C medium-entropy carbide(MEC)with a rock-salt structure.Attributed to the solid solution strengthening and twinning strengthening,the TiCO0.4/WC/0.5Mo2C sintered at 1900℃by spark plasma sintering(SPS)shows superior mechanical behaviors of microhardness(21.7 GPa),which exceeds that expected from the rule of mixture(ROM)of three individual metal carbides(19.1 GPa)and good fracture toughness(5.3 MPa m1/2).Significantly,the bulk synthesized via high-pressure and high-temperature(HPHT)sintering possesses smaller grain size and shows better comprehensive mechanical properties of microhardness(23.7 GPa)and fracture toughness(6.2 MPa m1/2).In addition,the effect of anion vacancies on the thermodynamic stability and synthesizability of TiC0.4/WC/0.5Mo2C was analyzed via quantitatively calculated entropy.Vacancies could significantly enhance the configuratio nal entropy of mixing of the solid phase.The introduction of vacancy defects may expand synthetic path for entropy-stabilized ceramics,especially for multi-component high tempe rature refractory ceramics.展开更多
In the present work, the PLLA mesophase formation and its kinetics at the advent of a chain mobility accelerator (polyethylene glycol (PEG)) are investigated by wide angle X-ray diffraction (WAXD) and time-resol...In the present work, the PLLA mesophase formation and its kinetics at the advent of a chain mobility accelerator (polyethylene glycol (PEG)) are investigated by wide angle X-ray diffraction (WAXD) and time-resolved Fourier transform infrared spectroscopy (FTIR). It is interestingly found that the presence of PEG could accelerate the formation of PLLA mesophase notably due to the enhanced chain mobility, giving rise to a substantially reduced half time (t0.5) of PLLA mesophase formation from 129 min to 8 min. The Avrami exponents (n) for the kinetics of mesophase formation are -0.5 for neat PLLA and 1 for PLLA/PEG, respectively, indicating that 1D-rod growth through heterogeneous nucleation occurs during formation of PLLA mesophase. Tensile testing demonstrates that PLLA mesophase could increase the tensile strength and modulus but decrease the elongation at break.展开更多
Advanced materials with superior comprehensive mechanical properties are strongly desired,but it has long been a challenge to achieve high ductility in high-strength materials.Here,we proposed a new V 0.5 Cr 0.5 CoNi ...Advanced materials with superior comprehensive mechanical properties are strongly desired,but it has long been a challenge to achieve high ductility in high-strength materials.Here,we proposed a new V 0.5 Cr 0.5 CoNi medium-entropy alloy(MEA)with a face-centered cubic/hexagonal close-packed(FCC/HCP)dual-phase ultrafine-grained(UFG)architecture containing stacking faults(SFs)and local chemical order(LCO)in HCP solid solution,to obtain an ultrahigh yield strength of 1476 MPa and uniform elongation of 13.2%at ambient temperature.The ultrahigh yield strength originates mainly from fine grain strength-ening of the UFG FCC matrix and HCP second-phase strengthening assisted by the SFs and LCO inside,whereas the large ductility correlates to the superior ability of the UFG FCC matrix to storage disloca-tions and the function of deformation-induced SFs in the vicinity of the FCC/HCP boundary to eliminate the stress concentration.This work provides new guidance by engineering novel composition and stable UFG structure for upgrading the mechanical properties of metallic materials.展开更多
1.Introduction Fracture toughness is the ability of materials against both the initiation and propagation of cracks[1],which is a crucial mechanical property for safety-critical applications of structural materials.Al...1.Introduction Fracture toughness is the ability of materials against both the initiation and propagation of cracks[1],which is a crucial mechanical property for safety-critical applications of structural materials.Although the yield strength of ceramics is significantly higher than that of metallic materials,the fracture toughness is severely lower than that of metallic materials due to the strongly directional covalent bonding[1-3].For a long time,how to improve the fracture toughness of ceramics without the deterioration of strength(or hardness)has been one of the most challenging problems in materials science.展开更多
基金supported by the China National Key R&D Program during the 14th Five-year Plan Period(2022YFD1901603)。
文摘Sugarcane/soybean intercropping with reduced nitrogen addition is an important sustainable agricultural pattern that can alter soil ecological functions,thereby affecting straw decomposition in the soil.However,the mechanisms underlying changes in soil organic carbon(SOC)composition and microbial communities during straw decomposition under long-term intercropping with reduced nitrogen addition remain unclear.In this study,we conducted an in-situ microplot incubation experiment with^(13)C-labeled soybean straw residue addition in a two-factor(cropping pattern:sugarcane monoculture(MS)and sugarcane/soybean intercropping(SB);nitrogen addition levels:reduced nitrogen addition(N1)and conventional nitrogen addition(N2))long-term experimental field plot.The results showed that the SBN1 treatment significantly increased the residual particulate organic carbon(POC)and residual microbial biomass carbon(MBC)contents during straw decomposition,and the straw carbon in soil was mainly conserved as POC.Straw addition changed the structure and reduced the diversity of the soil microbial community,but microbial diversity gradually recovered with decomposition time.During straw decomposition,the intercropping pattern significantly increased the relative abundances of Firmicutes and Ascomycota.In addition,straw addition reduced microbial network complexity in the sugarcane/soybean intercropping pattern but increased it in the sugarcane monoculture pattern.Nevertheless,microbial network complexity remained higher in the SBN1 treatment than in the MSN1 treatment.In general,the SBN1 treatment significantly increased the diversity of microbial communities and the relative abundance of microorganisms associated with organic matter decomposition,and the changes in microbial communities were mainly driven by the residual labile SOC fractions.These findings suggest that more straw carbon can be sequestered in the soil under sugarcane/soybean intercropping with reduced nitrogen addition to maintain microbial diversity and contribute to the development of sustainable agriculture.
基金supported by the Guizhou University Talent Introduction Program([2021]05)Guizhou University Cultivation Program([2020]48)+2 种基金Institute of Technology of YF([2022]017)Guizhou Province High-Level Innovative Talents“Hundred”Level Talent Project(Qiankehe Platform Talent)GCC[2023]014Supported by the earmarked fund for GZMARS-Tea and Research on the Planting Technology of China HUANENG Photovoltaic Tea Garden(Project No.HNKJ2022-H135).
文摘The ATP-binding cassette(ABC)transporter is a gene superfamily in plants.ATP-binding cassette subfamily C(ABCC)protein is a multidrug resistance-associated(MRP)transporter.They play various roles in plant growth,development,and secondary metabolite transport.However,there are few studies on ABCC transporters in tea plants.In this study,genome-wide association study(GWAS)analysis of epigallocatechin gallate(EGCG)content in 108 strains of Kingbird revealed that CsABCCs may be involved in EGCG transport.We identified 25 CsABCC genes at the genomic level of the tea plant,their phylogenetic tree,gene structure,targeted miRNA and other bioinformatics were analyzed.The expression patterns of CsABCCs in eight different tissues and abiotic stress indicate that they have potential roles in regulating the growth,development,and defense of tea plants.The correlation analysis revealed that the expression of the CsABCC11 gene was closely related to the EGCG content in tea buds of 108 strains of the Kingbird,and the subcellular localization experiments in tobacco showed that CsABCC11 protein was localized on the plasma membrane.The virus-induced gene silencing(VIGS)strategy in tea plants further verified that CsABCC11 was involved in EGCG accumulation.Our study laid a foundation for studying the biological function of CsABCC and provided a new candidate molecular marker gene for further EGCG-related variety breeding,which will be of great interest to breeders.
基金This study was supported by the National Key Research and Development Program of China(2023YFD2100403)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(CAAS-ASTIP-2021-OCRI)+2 种基金the earmarked fund for CARS-14,the Innovation Group Project of Hubei Province(2023AFA042)the Key Research Projects of Hubei Province(2020BBA045)the Knowledge Innovation Program of Wuhan-Basic Research(3562).
文摘The study explored the influence of defatted flaxseed gum powder(DFGP) on the stability and quality of sesame paste by measuring and analyzing its composition, color, texture, particle size, centrifugal oil separation rate,rheological properties, and microstructure. The results showed that the moisture and polysaccharide content of sesame paste was increased as the DFGP increased. Additionally, the hardness, gumminess, and chewiness of the sesame paste was improved, while the presence of particles with small particle size(1–100 μm) was decreased.The rate of oil precipitation was reduced by 28.99% when the amount of DFGP was 6%. The sesame paste samples exhibited pseudoplastic behavior, demonstrating shear thinning. As the shear rate increased, the apparent viscosity of sesame paste gradually decreased. Both the storage modulus(G’) and the loss modulus(G’’) increased as the shear frequency increased. The microstructure observation revealed that protein and oil were evenly distributed in the sesame paste system, and the addition of DFGP enhanced the bonding between oil and protein.This study can provide valuable references for high-quality sesame paste products in the food industry.
基金supported by the National Natural Science Foundation of China(3226180451,3226180488)Guizhou Province Outstanding Young Scientific and Technological Talent Cultivation Project(Qiankehe PlatformTalent[2019]5651)Guizhou Province Science and Technology Planning Project(Qiankehe Support[2021]General 111).
文摘Caffeine is considered as one of the most important bioactive components in the popular plant beverages tea,cacao,and coffee,but as a wide-spread plant secondary metabolite its biosynthetic regulation at transcription level remains largely unclear.Here,we report a novel transcription factor Camellia sinensis Senescnece 40(CsS40)as a caffeine biosynthesis regulator,which was discovered during screening a yeast expression library constructed from tea leaf cDNAs for activation of tea caffeine synthase(TCS1)promoter.Besides multiple hits of the non-self-activation CsS40 clones that bound to and activated TCS1 promoter in yeast-one-hybrid assays,a split-luciferase complementation assay demonstrated that CsS40 acts as a transcription factor to activate the CsTCS1 gene and EMSA assay also demonstrated that CsS40 bound to the TCS1 gene promoter.Consistently,immunofluorescence data indicated that CsS40-GFP fusion was localized in the nuclei of tobacco epidermal cells.The expression pattern of CsS40 in‘Fuding Dabai’developing leaves was opposite to that of TCS1;and knockdown and overexpression of CsS40 in tea leaf calli significantly increased and decreased TCS1 expression levels,respectively.The expression levels of CsS40 were also negatively correlated to caffeine accumulation in developing leaves and transgenic calli of‘Fuding Dabai’.Furthermore,overexpression of CsS40 reduced the accumulation of xanthine and hypoxanthine in tobacco plants,meanwhile,increased their susceptibility to aging.CsS40 expression in tea leaves was also induced by senescence-promoting hormones and environmental factors.Taken together,we showed that a novel senescence-related factor CsS40 negatively regulates TCS1 and represses caffeine accumulation in tea cultivar‘Fuding Dabai’.The study provides new insights into caffeine biosynthesis regulation by a plant-specific senescence regulator in tea plants in connection to leaf senescence and hormone signaling.
基金the National Key Research and Development Program of China(2019YFA0708502)the National Natural Science Foundation of China(Grant No.U1930401)+3 种基金BL14U1 of the Shanghai Synchrotron Radiation Facility for beamtime access based on proposal 2019-SSRF-PT-011035 and Geo-SoilEnviroCARS(Sector 13-BMC and 13-BMD)at the Advanced Photon Source,Argonne National Laboratory,USAthe National Science Foundation Earth Sciences(Grant No.EAR1128799)the Department of Energy-GeoSciences(Grant No.DEFG02-94ER14466)The Advanced Photon Source is a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle.δ-(Al_(0.956)Fe_(0.044))OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells.The incorporation of 5 mol%FeOOH increases the unit-cell volume ofδ-AlOOH by~1%and decreases the shear-wave velocity(VS)by~5%at 20–135 GPa.In particular,the compressional(V_(P))and shear(VS)wave velocities ofδ-(Al_(0.956)Fe_(0.044))OOH are 7%–16%and 10%–24%greater than all the major minerals in the mantle transition zone including wadsleyite,ringwoodite,and majorite.The distinctly high sound velocities ofδ-(Al_(0.956)Fe_(0.044))OOH at 20–25 GPa may contribute to the seismic anomalies observed at~560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea.Furthermore,the VS ofδ-(Al_(0.956)Fe_(0.044))OOH is about 10%and 4%–12%lower than iron-bearing bridgmanite Mg_(0.96)Fe_(0.05)Si_(0.99O3)and ferropericlase(Mg_(0.92)Fe_(0.08))O,respectively,under the lowermost mantle conditions,which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.10904093 and 61031003)the Science and Technology Grant Scheme funds from Shenzhen Government(No.08CXY-23).
文摘Being an emerging body-shaping technology of fat cell disruption,high-intensity focused ultrasound has been investigated intensively in recent years for its favorable natures such as painlessness,safety and noninvasion.One of the major problems for the technology,however,is the overheating of transducers.In this study,we modified the transducer design in order to solve the overheating problem.We simulated the performance of the modified design by finite element analysis and fabricated the newly designed transducer.By measuring the actual performance data,we proved that the new design can effectively reduce temperature rise while keeping the acoustic intensity field unaffected.
基金the National Natural Science Foundation of China(grant Nos.12272158 and 11872028).
文摘The collapse of granular material in fluids is a prevalent phenomenon in both natural and industrial processes,displaying a notable sensitivity to initial configuration of the system.This study is specifically oriented towards falling process of collapsing material under various fluid conditions,employing the computational fluid dynamics-discrete element method(CFD-DEM)to primarily investigate the dynamics and scaling laws of deposit morphology of collapsed material.Through a comprehensive analysis of particle sedimentation in fluids,we introduce a refined inertial characteristic time for granular collapse within the inertial regime.Subsequently,we propose modifications to conventional fluid-particle density ratio and Reynolds number,aiming to enhance the accuracy of depicting collapse dynamics and identifying flow regimes across diverse column heights and fluid conditions.Finally,we construct a phase diagram of flow regimes using modified dimensionless numbers,emphasizing the role of column height in transition between viscous and inertial regimes.These parameters demonstrate enhanced relevance in governing the collapse of immersed granular columns,thereby contributing to a more nuanced understanding of fluid-particle interations in dense granular flows under different regimes.
基金financially supported by the Natural Science Foundation of Hebei Province of China(Nos.E2016203425 and E2017203223)the Key Projects of Scientific and Technological Research in Hebei Province(No.ZD2017074)。
文摘Recently,high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness,fracture toughness,and conductivity.However,as a newly emerging class of materials,the synthesis,performance and applications of high-entropy ceramics are subject to further development.Here,we reported a new non-stoichiometric TiC0.4/WC/0.5Mo2C medium-entropy carbide(MEC)with a rock-salt structure.Attributed to the solid solution strengthening and twinning strengthening,the TiCO0.4/WC/0.5Mo2C sintered at 1900℃by spark plasma sintering(SPS)shows superior mechanical behaviors of microhardness(21.7 GPa),which exceeds that expected from the rule of mixture(ROM)of three individual metal carbides(19.1 GPa)and good fracture toughness(5.3 MPa m1/2).Significantly,the bulk synthesized via high-pressure and high-temperature(HPHT)sintering possesses smaller grain size and shows better comprehensive mechanical properties of microhardness(23.7 GPa)and fracture toughness(6.2 MPa m1/2).In addition,the effect of anion vacancies on the thermodynamic stability and synthesizability of TiC0.4/WC/0.5Mo2C was analyzed via quantitatively calculated entropy.Vacancies could significantly enhance the configuratio nal entropy of mixing of the solid phase.The introduction of vacancy defects may expand synthetic path for entropy-stabilized ceramics,especially for multi-component high tempe rature refractory ceramics.
基金financially supported by the National Natural Science Foundation of China(Nos.51120135002,51203104)the Doctoral Program of the Ministry of Education of China(No.20120181120101)+1 种基金the Program of Introducing Talents of Discipline to Universities(B13040)the Innovation Team Program of Science&Technology Department of Sichuan Province(No.2013TD0013)
文摘In the present work, the PLLA mesophase formation and its kinetics at the advent of a chain mobility accelerator (polyethylene glycol (PEG)) are investigated by wide angle X-ray diffraction (WAXD) and time-resolved Fourier transform infrared spectroscopy (FTIR). It is interestingly found that the presence of PEG could accelerate the formation of PLLA mesophase notably due to the enhanced chain mobility, giving rise to a substantially reduced half time (t0.5) of PLLA mesophase formation from 129 min to 8 min. The Avrami exponents (n) for the kinetics of mesophase formation are -0.5 for neat PLLA and 1 for PLLA/PEG, respectively, indicating that 1D-rod growth through heterogeneous nucleation occurs during formation of PLLA mesophase. Tensile testing demonstrates that PLLA mesophase could increase the tensile strength and modulus but decrease the elongation at break.
基金supported by the National Natural Science Foundation of China(Nos.U1530401,52071038,51871194)the Fundamental Research Funds for the Central Universities(No.N2102008)the Innovation Research Group Project of Hebei Natural Science Foundation,China(No.E2021203011).
文摘Advanced materials with superior comprehensive mechanical properties are strongly desired,but it has long been a challenge to achieve high ductility in high-strength materials.Here,we proposed a new V 0.5 Cr 0.5 CoNi medium-entropy alloy(MEA)with a face-centered cubic/hexagonal close-packed(FCC/HCP)dual-phase ultrafine-grained(UFG)architecture containing stacking faults(SFs)and local chemical order(LCO)in HCP solid solution,to obtain an ultrahigh yield strength of 1476 MPa and uniform elongation of 13.2%at ambient temperature.The ultrahigh yield strength originates mainly from fine grain strength-ening of the UFG FCC matrix and HCP second-phase strengthening assisted by the SFs and LCO inside,whereas the large ductility correlates to the superior ability of the UFG FCC matrix to storage disloca-tions and the function of deformation-induced SFs in the vicinity of the FCC/HCP boundary to eliminate the stress concentration.This work provides new guidance by engineering novel composition and stable UFG structure for upgrading the mechanical properties of metallic materials.
基金financially supported by the Natural Science Foundation of Hebei Province of China(Nos.E2016203425 and E2017203223)the Key Projects of Scientific and Technological Research in Hebei Province(No.ZD2017074)+1 种基金the National Natural Science Foundation of China(No.12075215)the Science and Technology Project of Hebei Education Department(No.QN2021136 and ZD2017026)。
文摘1.Introduction Fracture toughness is the ability of materials against both the initiation and propagation of cracks[1],which is a crucial mechanical property for safety-critical applications of structural materials.Although the yield strength of ceramics is significantly higher than that of metallic materials,the fracture toughness is severely lower than that of metallic materials due to the strongly directional covalent bonding[1-3].For a long time,how to improve the fracture toughness of ceramics without the deterioration of strength(or hardness)has been one of the most challenging problems in materials science.